The present invention is directed generally to a combination fireplace furnace unit and more particularly to a failsafe damper adapted to close at least one of the heat outlets thereof whenever the furnace blower is inoperative.
Auxiliary fireplace furnaces have become increasingly popular in recent years due to the escalating cost of operating conventional oil, gas and electric furnaces. By connecting the heat outlet of a fireplace furnace to the air distribution duct work of a building, heat from the fireplace may be distributed throughout the house to supplement or replace heating by the conventional furnace.
Excessive temperature buildup within the heat chamber is normally prevented by the continuous flow of intake air through the heat chamber by the blowers. In the event of a power failure or breakdown of the blower, however, the temperature within the heat chamber may rise to approximately 900.degree. F. If this 900.degree. air is allowed to rise by convection into the building duct work, a fire hazard may be created due to the proximity of combustible construction materials adjacent the duct work. Another heat outlet from the heat chamber may open through a masonry wall or the like into the room in which the fireplace is situated so that hot air exiting therethrough is substantially dissipated and cooled before contacting any combustible surfaces. There is a need therefore for a failsafe means of closing the fireplace furnace outlets which communicate with the building duct work, whenever the blowers cease to operate.
The present invention proposes to provide a damper within the heat outlet to the building duct work, which damper is adapted to close whenever the blowers are inoperative. But horizontally disposed dampers which are commercially available have been found to be unsuitable. The check valve-type dampers which include a seated valve element experience critical lubrication problems at very high temperatures. Likewise, power actuated dampers and thermostatically controlled dampers would generally burn out well before the heat chamber temperature reaches its maximum level.
A further problem related to the connection of an auxiliary fireplace furnace to the air distribution duct work of a building is that, when the fireplace furnace is inoperative, backflow of the forced air from the main furnace or air conditioning unit through the fireplace furnace must be prevented.
Accordingly, it is a primary object of the present invention to provide a failsafe protection damper for a fireplace furnace.
Another object is to provide a damper in the heat outlet of a fireplace furnace, which damper is adapted to close whenever the fireplace blowers are inoperative.
Another object is to provide a fireplace furnace damper adapted to prevent the backflow of forced air from a conventional furnace unit into the fireplace furnace.